I normally recognize them by grey skin, thin, face pitted or wrinkled, etc. Makes them look 10-30 years older than they should look.
What you mention are the signs of long term heavy use. Constantly moving/fidgety is another sign of meth use. You'll see people like that that still look pretty normal physically. Once in a while I'll be in the car, stopped at a light, and look in the mirror and see a tweaker just a movin'! Looking this way/that way. doing something on the seat beside them/in the glove box. Yep! TWEAKER!